Over the past years there has been increasing interest in the design and development of packaging of the type so called "child resistant," that is to say, packaging designed so that it cannot be opened accidentally or intentionally by children without special manipulation of the closure. Such packaging has found use for pharmaceuticals and harmful compositions which are used in the home with which children are likely to come into contact. This interest has led to the development of standards and testing procedures by various governmental and international agencies.
Numerous designs for such packaging are available and they can be said generally to fall into two major categories: packaging having closures of multi-component design, and packaging having closures in which the locking elements are integrally formed as part of the closure. Single component closures are normally designed to be removed by manipulating the closure in a manner that is difficult for children. Single component closures are preferred, since they can be more easily and economically manufactured using mass production methods. Examples of such child resistant packaging utilizing single component closures are to be found in my U.S. Pat. Nos. 3,952,899, 4,139,112 and 4,434,903. Examples of other single piece closures are found in U.S. Pat. No. Re. 27,156 (Hedgewick), U.S. Pat. No. 3,880,314 (Ackers), U.S. Pat. No. 3,779,001 (Bogert), U.S. Pat. No. 4,032,028 (Reiss et al.) and U.S. Pat. No. 4,119,232 (Thornton).
In packaging of the type to which this invention relates, there is a high probability that the closure will be removed forcibly without proper manipulation which will result in damage to the locking elements rendering the package inoperable with respect to the locking feature. In this regard many specifications for child resistant packages call for testing of the package to determine its ability to withstand the forced removal of the closure and its ability to retain the locking feature even after such forced removal.